Filament supports for electric incandescent lamps



Feb. 2, 1965 v. A. LEVAND, JR 0 FILAMENT SUPPORTS FOR ELECTRIC INCANDESCENT LAMPS Filed March 25. 1961 lrwvan tor 1 Victor A. Levandfln b Wf' 9 His A tggy neg This invention relates generally to electric incandescent lamps, and more particularly to electric lamps comprising tubular elongated envelopes containing an axially extending helicaily coiled filament Whichis supported from the inner envelope Wall by one or more support members spaced along the length of the filament.

In certain lamp types of the character described above,

the filament support members have been made of wire coiled to a generally spiral configuration engageable with the inner wall of the envelope and terminating in a central coil portion consisting of a helical coil of about two turns. After winding the support members about a mandrel, they were stripped off the mandrel and assembled with the filament coil by screwing the central coiled portion or" the support over the filament coil. That method is obviously time consuming, particularly when a rather large number of support members are attached to a single coil as, for example, when a filament coil ten inches long is supplied with eight such supports. Attempts to wind the supports directly onto the filament coil proved to be unsatisfactory because the support wire separated the turns of the filament coil and was easily displaced relative thereto when subjected to shock or vibration.

It is therefore an object of the invention to provide a form of support member and a method of forming and assembling the support member directly onto the filament coil which results in a structure whereby the support member is firmly loci-red and centered concentrically on the filament coil.

In accordance with one aspect of the invention, the support members are wound and installed directly on United States Patent the filament coil by winding a length of support wire about the filament coil, preferably to a spiral form, continuirig the coiling of the wire at the center of the spiral to form primary helical turns which are wound in the same 1 elical sense as the filament and are concentric with and fit between turns of the filament coil, and then further continuing the coiling of the support wire in the opposite helical sense to form one or more locking turns overlying the said turns of the filament coil and said primary helical turns. The resulting support members are of uniform size and shape, and are securely attached to the filament coil and concentrically centered thereon.

Further features and advantages of the invention will appear from the following detailed description of a species thereof and from the drawing wherein:

Fit}. 1 is a side view of a form of lamp embodying support members in accordance with the invention;

FIG. 2 is a fragmentary side view partly in section along the line 22 in FIG. 3, and on an enlarged scale, showing the manner of attachment of a support to the filament coil;

FIG. 3 is a front view of the structure shown in FIG, 2;

FIG. 4 is a perspective View of a support forming mandrel or spindle;

FIG. 5 is a front view of the face of the support forming mandrel; and

FIG. 6 is a section through the support forming mandrel and associated supporting mechanism for the filament coil, taken along the line 66 in FIG. 5.

Referring to FIG. 1 of the drawing, the lamp illustrated therein, and which may be of the type shown in arrears Patented Feb. 2, 1965 Patent 2,883,57l-Fridrich et 211., comprises a tubular envelope ll of vitreous material such as quartz containing a gas filling such as argon and a small quantity of iodine vapor. A helically coiled tungsten wire filament 2 extends axially of the envelope 1 and is connected at its ends to the inner ends of lead-in conductor 3 which extend outwardly through compressed pinch seal portions 4- at the ends of the envelope. The filament 2 is supported from the inner walls of the envelope 1 by support members 5 attached to the filament at spaced points therealong and engageable with the inner walls of the envelope.

Each of the support members 5 (FIGS. 2 and 3) is formed of wire, for example tungsten wire, and includes an outer coiled turn portion 6 of slightly smaller diameter than the inner diameter of the envelope 1 to be engageable therewith. The said outer coil turn portion is connected by an intermediate portion 7, preferably of spiral form, with a central coiled portion engaging the filament coil 2 and including primary helical turns 8, preferably two full turns, which are concentric with and located between turns of the filament coil 2. The said primary turns 8 terminate in helical locking turns, preferably one full turn 9, of opposite helical sense and overlying the turns of the filament coil 2 and said primary turns 3. The overwind of locking turn 9 assures a firm attachment and centering of the support 5 on the filament coil 2.

The support 5 is formed about and installed directly on the filament coil 2, preferably by mechanisms like that shown in FIGS. 4-6. The filament coil 2, containing a closely fitting mandrel wire it (FIG. 6), is inserted into an axial bore 11 in a rotatable forming mandrel or spindle l2 and into a collet chuck 13 in the interior of the mandrel 12;. The spring finger portions of the chuck iii are held normally closed by being pressed against the tapered end id of the enlarged axial opening 15 by a spring loaded tube lid into which the filament 2 also extends. The tube 15 is pulled back to relieve the fingers of collet chuck 13 to open position during loading of the filament Z therein.

The end of a length of supportforming wire is inserted into a passage 17 adjacent the front face of the mandrel l2 and the wire is bent down into the groove 18 in the periphery of the mandrel. The mandrel, together with the coil 2, is then rotated clockwise, as viewed in FIG. 5, to form the length of support wire around the tapered portion 19 of the groove 18 on the front face of the mandrel l2 and onto the spiral grooved track 20 at the center of the mandrel face From the inner end of the spiral track Ztl, the wire runsdown onto the Wire mandrel it between turns of the filament coil 2 to form the two helical turns 8 (FIG. 2). The direction of coiling is then reversed by urging the length of support wire in the direction opposite to the helical sense of the filament coil 2:, to thereby form the locking overwind 9 (FIG. 2). The len th of support Wire is then cut off from the overwind turn h. The formed portion of the wire is then severed at a point where it crosses over the notch 21 to release it from the end portion caught in the passage 17, after which it is severed at a point corresponding to the beginning of the central spiral track 20 to leave the formed support as shown in FIG. 3. The grip of the collet chuck 13 is then released by temporarily retracting the spring loaded tube 16, and the filament coil 2 and mandrel 10 are pulled forward a predetermined distance for forming and attachment of the next support member 5 to the filament coil 2.

The above recited operations are quickly performed, even on semiautomatic equipment, with a very considerable saving of time over the prior practice ofseparately forming the support members and screwing them onto the filament coil. The resulting support member 5 is also securely fastened to the filament coil 2 in a manner not heretofore achieved.

' What I claim as new and desire to secure by Letters Patent of the United States is:

1. In an electric lamp comprising a tubular envelope having a helically coiled wire filament extending axially thereof and supported intermediate its ends from the inner Wall of said envelope by at least one support memher, said support member comprising a wire having an outer coiled turn portion engageable with the inner wall of said envelope and connecting with a central coiled portion engaging the filament coil, said central coiled portion including primary helical turns concentric with and located between turns of said filament coil and terminating in secondary helical locking turns of opposite helical sense tightly overlying said turns of the filament coil and said primary helical turns.

2. In an electric lamp comprising a tubular envelope having a helically coiled Wire filament extending axially I thereof and supported intermediate its ends from the inner Wall of said envelope by at least one support member, said support member comprising a continuous wire having a portion of substantially spiral form engageable at its periphery with the inner Wall of said envelope and a central coiled portion engaging the filament coil, said central coiled portion including primary helical turns concentric with and located between turns of said filament coil and terminating in secondary helical locking turns of opposite helical sense tightly overlying said turns of the filament coil and said primary helical turns.

References Cit-ed in the file of this patent UNITED STATES PATENTS 2,342,044 Foote Feb. 15, 1944 2,864,025 Foote et al Dec. 9, 1953 FOREIGN PATENTS 834,087 Great Britain May 4, 1960 

1. IN AN ELECTRICAL LAMP COMPRISING A TUBULAR ENVELOPE HAVING A HELICALLY COILED WIRE FILAMENT EXTENDING AXIALLY THEREOF AND SUPPORTED INTERMEDIATE ITS ENDS FROM THE INNER WALL OF SAID ENVELOPE BY AT LEAST ONE SUPPORT MEMBER, SAID SUPPORT MEMBER COMPRISING A WIRE HAVING AN OUTER COILED TURN PORTION ENGAGEABLE WITH THE INNER WALL OF SAID ENVELOPE AND CONNECTING WITH A CENTRAL COILED PORTION ENGAGING THE FILAMENT COIL, SAID CENTRAL COILED PORTION INCLUDING PRIMARY HELICAL TURNS CONCENTRIC WITH AND LOCATED BETWEEN TURNS OF SAID FILAMENT COIL AND TERMINATING IN SECONDARY HELICAL LOCKING TURNS OF OPPOSITE HELICAL SENSE TIGHTLY OVERLYING SAID TURNS OF THE FILAMENT COIL AND SAID PRIMARY HELICAL TURNS. 